16/12/2015-tyw-Docosahexaenoic Acid (DHA)（3）
Total Retina DHA Flux Unknown
视网膜总DHA通量未知
First off, you'll see places which state that “DHA is 60% of the Retina's lipis”.
I honestly couldn't find a study which supported that claim:
首先，你会看到“DHA占视网膜唇部的60%”。
老实说，我找不到任何研究支持这一说法:
•'Fatty acid composition of brain, retina, and erythrocytes in breast- and formula-fed infants.' (Makrides et. al., 1994) – http://www.ncbi.nlm.nih.gov/pubmed/7913291，Infant study, so I'd expect a lower DHA concentration. DHA is 12.3 +- 2.1% of total fatty acids by weight in the High DHA diet.
•'Fatty acid composition of the human macula and peripheral retina.' (F J van Kuijk and P Buck, 1992) – http://iovs.arvojournals.org/article.aspx?articleid=2178624
DHA 15.9% of total fatty acids in macular, 22.3% in the peripheral retina.
•'Lipids of human retina, retinal pigment epithelium, and Bruch's membrane/choroid: comparison of macular and peripheral regions.' (Gülcan et. al., 1993) – http://iovs.arvojournals.org/article.aspx?articleid=2160942
•In Phospholipids: DHA consists 8.4 +- 2.1% total lipids in the macular, 9.4 +- 2.0%
•in the peripheryIn Neutral Lipids: DHA consists 3.3 +- 2.5% total lipids in the macular, 2.6 +- 0.9% in the periphery.
•“母乳喂养和配方奶喂养的婴儿大脑、视网膜和红细胞的脂肪酸组成。(Makrides等，1994)——http://www.ncbi.nlm.nih.gov/pubmed/7913291，婴儿研究，所以我认为DHA浓度较低。在高DHA饮食中，DHA占总脂肪酸体重的12.3 +- 2.1%。
•“人体黄斑和周围视网膜的脂肪酸组成。(F J van Kuijk and P Buck, 1992)——http://iovs.arvojournals.org/article.aspx?articleid=2178624
DHA占黄斑总脂肪酸的15.9%，占视网膜外周总脂肪酸的22.3%。
•人类视网膜、视网膜色素上皮和Bruch膜/脉络膜的脂质:黄斑和周围区域的比较。(Gülcan等，1993)——http://iovs.arvojournals.org/article.aspx?articleid=2160942
•在磷脂方面:DHA在黄斑中占总脂类的8.4±2.1%，在外围为9.4±2.0%
•在中性脂类中:DHA在黄斑中占总脂类的3.3 +- 2.5%，在外围2.6 +- 0.9%
There are about 5 times as much Neutral Lipids compared to Phospholipids in the retina (Figure 3 in paper), so the total amount of DHA is more akin to (8.4 + 9.4) * 1/6 + (3.3 + 2.6) * 5/6 = 7.883% on average.
The DHA content of the Retinal Pigment Epithelium and Bruch's Membrane / Choroid are very low, less than 1% of total fatty acids in either of the Macula or Periphery.
In any case, it's not as high as purported, though 20+% of total lipids is still a lot.
视网膜中中性脂类的含量大约是磷脂的5倍(图3)，所以DHA的总量更接近(8.4 + 9.4)* 1/6 +(3.3 + 2.6)* 5/6 = 7.883%。
DHA在视网膜色素上皮和Bruch膜/脉络膜中的含量很低，在黄斑或周围的总脂肪酸中不到1%。
无论如何，这并不像传闻的那么高，尽管20%以上的总脂类仍然很多。
Much more important questions are:
•How much DHA does the entire eye contain (mass)?
•How much DHA gets recyled on a daily basis (mass)?
We need to know answers to these questions, and the factors which influence the answers, to be able to say if endogenous DHA synthesis rates can meet retinal DHA demands (and therefore actually support the need for lower DHA intake), and to actually define DHA demands.
更重要的问题是:
•整个眼睛含有多少DHA(质量)?
•每天回收多少DHA(质量)?
我们需要知道这些问题的答案，以及影响这些答案的因素，从而能够说出内源性DHA合成率是否能够满足视网膜对DHA的需求(因此实际上支持低DHA摄入量的需求)，并确定DHA的需求。
The entire eye is probably something like 7.5g. And the retina is tiny … 1,094 mm^2 area with maximum thickness of 400 um, according to 'Facts and Figures Concerning the Human Retina' (Helga Kolb, 2005) – http://www.ncbi.nlm.nih.gov/books/NBK11556/.
整个眼睛大概是7.5克左右。视网膜很小…根据“关于人类视网膜的事实和数据”(Helga Kolb, 2005)——http://www.ncbi.nlm.nih.gov/books/NBK11556/。
That is at best: 1094 * 10^-2 * 400 * 10^-4 = 0.4376 cm^3 of volume.
(Assuming a uniformly thick retina, which it is not – average thickness will be less)
I have no clue how much of this volume is lipid, and how much of it consists fatty acids, nor do I know what the density of said proteins and fatty acids are in the retina. But I would think that retina mass is mostly protein.
Regardless, assuming a (more than generous) 1g/cm^3 density for fatty acids, and 50% of the retina volume as pure fatty acids (which it is not), and 20% of those fatty acids being DHA (high estimate), that's 0.4376 * 0.5 * 0.2 * 1.0 = 0.04376g / 43.76mg of DHA.
How much of it gets turned over every day? No clue.
这最多是:1094 * 10^-2 * 400 * 10^-4 = 0.4376 cm^3的体积。
(假设视网膜是均匀厚的，其实不是——平均厚度会小一些)
我不知道这个体积中有多少是脂质，有多少是脂肪酸，也不知道视网膜中蛋白质和脂肪酸的密度是多少。但我认为视网膜大部分是蛋白质。
无论如何，假设脂肪酸的密度是(非常高)1克/厘米^3，视网膜体积的50%是纯脂肪酸(其实不是)，而这些脂肪酸的20%是DHA(高估计)，那就是0.4376 * 0.5 * 0.2 * 1.0 = 0.04376克/ 43.76毫克DHA。
每天有多少被翻过来?没有线索。
I do not dispute that DHA is important for the eye in general. But focusing on something like DHA for eye health is missing all the other components of the human eye. Everything from the time light hits the cornea, to transversal the complex and not-well-understood optically active medium of the vitreous humour, to finally hitting the retine, and then the response to that signal, is all going to be equally important in “eye health”.
And how aout looking at all those 3000+ proteins in 'The proteome of human retina.'(Zhang et. al., 2015) – http://www.ncbi.nlm.nih.gov/pubmed/25407473
总的来说，我并不否认DHA对眼睛的重要性。但是，关注DHA等物质对眼睛健康的影响，就忽略了人眼的其他成分。从光线照射到角膜的时间，到穿过复杂的、不太了解的光学活性介质玻璃体，再到最后照射到视网膜，然后是对信号的反应，这一切对“眼睛健康”都将是同样重要的。
看看《人类视网膜的蛋白质组》里的3000多个蛋白质。(张等人，2015)——http://www.ncbi.nlm.nih.gov/pubmed/25407473
Clinical trials also don't seem to show any improvement with DHA supplementation in sick eyes, 'Lutein + Zeaxanthin and Omega-3 Fatty Acids for Age-Related Macular Degeneration. The Age-Related Eye Disease Study 2 (AREDS2) Randomized Clinical Trial' (The Age-Related Eye Disease Study 2 (AREDS2) Research Group, 2013) – http://jama.jamanetwork.com/article.aspx?articleid=1684847
In this large, multicenter, placebo-controlled clinical trial in people at high risk for progression to advanced AMD, daily supplementation with lutein + zeaxanthin, DHA + EPA, or lutein + zeaxanthin and DHA + EPA in addition to the original AREDS formulation showed no statistically significant overall effect on progression to advanced AMD or changes in visual acuity. Primary, secondary, and subgroup analyses demonstrated no beneficial or harmful effects of DHA + EPA for treatment of AMD. These null results may be attributable to the true lack of efficacy.
临床试验似乎也没有显示，补充DHA对患病眼睛的治疗效果有任何改善，叶黄素+玉米黄质和Omega-3脂肪酸对老年性黄斑变性的治疗效果也没有改善。年龄相关性眼病研究2 (AREDS2)随机临床试验“(年龄相关性眼病研究2 (AREDS2)研究组，2013)—http://jama.jamanetwork.com/article.aspx?articleid=1684847
在这项大型、多中心、安慰剂对照的临床试验中，研究对象是AMD进展的高危人群，每天补充叶黄素+玉米黄质DHA + EPA，或叶黄素+玉米黄质和DHA + EPA，除了原来的AREDS配方外，对进展到晚期AMD或视力变化没有统计上显著的整体影响。原发性、继发性和亚组分析显示DHA + EPA对AMD治疗无有益或有害影响。这些无效结果可能是由于真正缺乏疗效。
It's more likely that these people were sick to begin with, and that dysfunction caused their eye issues, including a possible dysregulation of DHA delivery to the retina. It isn't the lack of DHA that is the problem. It's the regulatory mechanisms that are screwed (and which can't be fixed simply by adding more DHA).
更有可能的是，这些人一开始就生病了，而功能障碍导致了他们的眼睛问题，包括可能的DHA输送到视网膜的失调。问题并不在于DHA的缺乏。这是调节机制被拧坏了(并不能简单地通过增加DHA来修复)。
Mitochondrial Respiration
线粒体呼吸
Good mitochondrial respiration is clearly very important. Ideally, you want your mitochodnria to be able to generate a lot of ATP and CO2, while making “correct” decisions in the face of nutrient excess, scarcity, or other stressors.
A thorough discussion of mitochondrial mechanics deserves its own article, but it's safe to assume that maximisation of the potential of forward electron flow Complex 1 activity is the goal (because in disease states like cancer ubiquitously, we see a failure of Complex 1).
良好的线粒体呼吸显然非常重要。理想情况下，你希望你的线粒体能够产生大量的ATP和CO2，同时在面对营养过剩、缺乏或其他压力源时做出“正确”的决定。
线粒体力学的全面讨论值得写一篇文章，但可以肯定的是，我们的目标是将前向电子流Complex 1活动的潜力最大化(因为在癌症等疾病的普遍状态下，我们看到Complex 1的失败)。
From that perspective, we can investigate if DHA and other PUFAs help or hurt this process, and by what mechanisms do they do so.
In general, PUFAs are insulin sensitising when oxidised as fuel based on the FADH2:NADH ratio. Peter @ Hyperlipid gives you the details – http://high-fat-nutrition.blogspot.com/2012/08/protons-fadh2nadh-ratios-and-mufa.html , but it's mainly a function of how much Complex 1 vs Complex 2 activity is taking place.
PUFAs tend to support higher mitochodnrial membrane potential, greater insulin sensitivity, and lower superoxide levels. On a purely mitochondrial kinetic basis (ignoring all the other harmful effects of PUFAs), this is a bad thing in the context of a high fat diet (you want physiologic insulin resistance), and good in the context of a high carbohydrate diet.
从这个角度来看，我们可以研究DHA和其他不饱和脂肪酸是否有助于或损害这个过程，以及它们是通过什么机制起作用的。
一般来说，当PUFAs被氧化为燃料时，根据FADH2:NADH的比例，会使胰岛素增敏。彼得@ hyper血脂为您提供了详细信息，http://high-fat-nutrition.blogspot.com/2012/08/protons-fadh2nadh-ratios-and-mufa.html，但这主要是关于复合物1和复合物2的活动发生了多少的函数。
PUFAs倾向于支持更高的线粒体膜电位、更高的胰岛素敏感性和更低的超氧化物水平。在纯线粒体动力学的基础上(忽略PUFAs的所有其他有害影响)，这在高脂肪饮食的背景下是一件坏事(你想要生理胰岛素抵抗)，而在高碳水化合物饮食的背景下是一件好事。
Again, this is just a discussion of pure forward-flow mitochondrial mechanics with regard to PUFA. All the bad effects of PUFAs are good reason to avoid them as much as possible.
As for DHA, we do not know how much DHA is put through beta-oxidation in a particular person, but if it is, then it will have a very low FADH2:NADH ratio, and consequently behave like any other PUFA put through Electron Chain Transport (ECT), and be very insulin sensitising.
再次强调，这只是关于多酚a的纯向前流线粒体力学的讨论。所有PUFAs的不良影响都是尽量避免使用的好理由。
至于DHA，我们不知道在一个特定的人体内有多少DHA通过β -氧化，但如果是，那么它将具有非常低的FADH2:NADH比率，并因此表现为通过电子链运输(ECT)的任何其他PUFA，并具有非常高的胰岛素敏感性。
DHA Membrane Incorporation
DHA膜合并
The more interesting effects of DHA happen when it is incorporated into the mitochondrial membranes, which apparently happens readily in rats (and probably humans too), 'Incorporation of marine lipids into mitochondrial membranes increases susceptibility to damage by calcium and reactive oxygen species: evidence for enhanced activation of phospholipase A2 in mitochondria enriched with n-3 fatty acids.'(Malis et. al., 1990) –http://www.pnas.org/content/87/22/8845.short
The researches fed Sprague-Dawley rats fish oil or beef fat, and then performed respiratory experiments on isolated Renal corticol mitochondrial.
当DHA与线粒体膜结合时，会产生更有趣的效果，这在老鼠身上很容易发生(可能人类也会发生)。n-3脂肪酸丰富的线粒体磷脂酶A2活化增强的证据。(Malis et al.， 1990)——http://www.pnas.org/content/87/22/8845.short
研究人员给斯普拉格-道利大鼠喂食鱼油或牛肉脂肪，然后对分离的肾皮质线粒体进行呼吸实验。
The amount of DHA on mitochondrial membranes (no distinction between inner and outer membrane) was close to triple the amount in the fish oil fed rats, so obviously the amount of DHA being fed managed to make it into the mitochondria of the kidneys.
DHA在线粒体膜上的含量(内膜和外膜没有区别)接近鱼油喂养大鼠的三倍，因此很明显，被喂养的DHA能够进入肾脏的线粒体。
Taking a look at the results, when DHA is high in the mitochondrial membranes, compared to when it is low:
•we see a slight drop in succinate driven respiration (Complex 2)
•a more significant drop in pyruvate/malate driven respiration (presumably representative of Complex 1 activity) [Figure 3]
•a very significant drop in respiration with pyruvate/malate upon exposure to Ca2+ and ypoxanthine (HX) xanthine oxidase (XO) (both generate reactive oxygen species) [Figure 3]
•a reduction in uncoupling with pyruvate/malate, especially when exposed to Ca2+ and ROS [Figure 4]
•an increase in uncoupling with succinate under any condition [Figure 4]
看看结果，当DHA在线粒体膜中含量高时，与DHA含量低时相比:
•琥珀酸驱动的呼吸略有下降(complex 2)
•丙酮酸/苹果酸驱动的呼吸作用更显著的下降(可能代表Complex 1的活性)[图3]
•在暴露于Ca2+和氧黄嘌呤(HX)黄嘌呤氧化酶(XO)时，丙酮酸/苹果酸的呼吸作用显著下降(两者都产生活性氧)[图3]
•丙酮酸盐/苹果酸盐解偶联减少，特别是当暴露于Ca2+和ROS时[图4]
•在任何条件下与琥珀酸解耦的增加[图4]
Note that in general, high Ca2+ and ROS suppressed respiration in this experiment, but the high DHA mitochondria reacted with a larger suppression overall.
Another note is that the DHA was likely oxidised by high ROS:
Afterexposure to reactive oxygen species (HX/XO), A4Ach [20:4(n-6)], EPA [20:5(n-3)],and DHA [22:6(n-3)] content decreased significantly.
That's not surprising given the instability of PUFAs in general, and would produce harmful by-products as a result.
注意，在本实验中，一般来说，高Ca2+和ROS抑制呼吸，但高DHA线粒体的反应总体上有更大的抑制。
另一个值得注意的是DHA很可能被高ROS氧化:
活性氧(HX/XO)、A4Ach [20:4(n-6)]、EPA [20:5(n-3)]和DHA [22:6(n-3)]暴露后含量显著降低。
考虑到多不饱和脂肪酸的不稳定性，这并不奇怪，而且还会产生有害的副产品。
Looking at Table 1 and 2 shows much higher release of FFAs from the membranes of Fish-oil fed mice mitochondria after the experiments (as compared to the beef fat fed mice mitochondria).
When compared with Fish Oil mitochondria, Beef Tallow mitochondria showed fewer changes in phospholipid fatty acid composition after the same level of exposure to Ca2+ and reactive oxygen species.
从表1和表2可以看出，实验结束后，鱼油喂养的小鼠线粒体膜释放的FFAs要比牛油喂养的小鼠线粒体高得多。
与鱼油线粒体相比，牛油线粒体在同样水平的Ca2+和活性氧暴露后磷脂脂肪酸组成变化较少。
They also look at Phospholipase A2 (PLA2) function, and found:
We have reported (18) that dibucaine., a PLA2 inhibitor (23), protected mitochondria against functional defects induced by Ca2+ and reactive oxygen species.
Dibucaine:
(i) protected the electron transport chain, presumably at the level of NADH, CoQreductase;
(ii) preserved Fl-ATPase and ADP translocaseactivity; and
(iii) prevented complete uncoupling of mitochondrial respiration
They then show a reduction in released 18:2, 20:4, and 20:5 FFAs during Ca2+ and ROS stress, but there was no change in apparent volatility of DHA. This was probably somewhat expected, given that DHA has the most number of double bonds, and is likely the “most reactive”.
他们还研究了磷脂酶A2 (PLA2)的功能，发现:
我们已经报道过(18)双布卡因。一种PLA2抑制剂(23)，保护线粒体免受Ca2+和活性氧诱导的功能缺陷。
双布卡因:
(i)在NADH, CoQreductase水平上保护电子传递链;
(ii)保留了Fl-ATPase和ADP转位酶活性;和
(iii)阻止线粒体呼吸完全解耦
然后，在Ca2+和ROS胁迫下，他们释放的18:2、20:4和20:5 FFAs减少，但DHA的表观挥发性没有变化。这在某种程度上可能是预料之中的，因为DHA拥有最多的双键，而且很可能是“最活跃的”。
The researchers claim:
PLA2 activation is believed to contribute to tissue injury in a number of pathophysiological processes in kidney (17,24), brain (25), heart (26,27), and liver (28). We have suggested (18) that PLA2 activation played an important role in Ca2+ and reactive oxygen species-induced injury to mitochondria.
and:
Membranes enriched with high unsaturated n-3 fatty acids would be more susceptible to peroxidation by reactive oxygen species, with generation of toxic lipid hydroperoxides (29), propagating further damage.
Peroxidized fatty acids may also potentiate activation of PLFA2 (7), which would amplify the injury.
The increased levels of FFAs would in turn likely increase membrane permeability to Ca2+ (16), which might further activate PLA2.
研究人员声称:
PLA2激活被认为在肾脏(17,24)、大脑(25)、心脏(26,27)和肝脏(28)的许多病理生理过程中导致组织损伤。我们认为(18)PLA2的激活在Ca2+和活性氧诱导的线粒体损伤中起重要作用。
和:
富含高不饱和n-3脂肪酸的膜更容易受到活性氧的过氧化作用，产生有毒的脂质氢过氧化物(29)，进一步传播损害。
过氧化物脂肪酸也可能增强PLFA2的激活(7)，这将放大损伤。
升高的FFAs水平可能会增加细胞膜对Ca2+的渗透性(16)，这可能会进一步激活PLA2。
That's a vicious cascade of injurious events …. Excess DHA is not a good thing for mitochondria.
On top of that you have increased proton permeability, and supposedly less ATP generation, specifically through defects at Complex 1. Again, not good.
这是一个恶性的连锁伤害事件….过量的DHA对线粒体来说不是好事。
最重要的是，你增加了质子渗透性，并且据说减少了ATP的生成，特别是通过复合物1的缺陷。再一次,不好。
Another study, 'Complex I-Associated Hydrogen Peroxide Production Is Decreased and Electron Transport Chain Enzyme Activities Are Altered in n-3 Enriched fat-1 Mice' (Hagopian et. al., 2010) – http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012696
Note that this study uses a specific type of transgenic mice:
These mice express the fat-1 gene from C. elegans, which encodes a desaturase that uses n-6 fatty acids as a substrate for the formation of n-3 fatty acids [21]. Transgenic fat-1 mice express this gene ubiquitously and thus provide a model to investigate the effect of increasing tissue n-3 fatty acid levels without the need for dietary intervention to achieve this goal.
This helps avoid the challenge of developing diets that truly differ only in the specific fatty acids of interest.
另一项研究“n-3强化脂肪-1小鼠中复合物i相关的过氧化氢生成减少，电子传递链酶活性改变”(Hagopian等，2010)——http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012696
请注意，这项研究使用了一种特殊类型的转基因小鼠:
这些小鼠表达来自秀丽隐杆线虫的脂肪-1基因，该基因编码一种以n-6脂肪酸为底物形成n-3脂肪酸[21]的去饱和酶。转基因fat-1小鼠普遍表达该基因，因此提供了一个模型来研究在不需要饮食干预的情况下增加组织n-3脂肪酸水平的影响。
这有助于避免开发只在特定脂肪酸方面真正不同的饮食所面临的挑战。
In any case, it is the DHA on the mitochondria that that we are interested in, and from Table 2, we find that the liver mitochondria of the modified rats had about 22% more Phophatidylcholine (PC) DHA and 24% more phophatidylethanolamine (PE) DHA.
There was no difference in coenzyme Q activity.
无论如何，我们感兴趣的是线粒体上的DHA，从表2中我们发现，转基因大鼠肝脏线粒体中磷脂酰胆碱(PC) DHA和磷脂酰乙醇胺(PE) DHA含量分别增加了22%和24%。
辅酶Q活性无差异。
Results:
To investigate a system which also includes coenzyme Q, we also measured Complex I+III and Complex II+III activities.
The activity of Complex I was decreased by 19% (p<0.05) in the fat-1 compared to control mice.
In contrast, the activities of Complex III and Complex IV were increased by 58% (p<0.01) and 27% (p<0.05), respectively, in liver mitochondria from the fat-1 mice.
The decreased Complex I activity was not sufficient to cause an overall decrease in Complex I+III activity, and in fact there was a 19% increase (p<0.05) in Complex I+III activity in the fat-1 animals.
The activities of Complex II and Complex II+III were not significantly different between control and fat-1 mice.
The activities of Complex I+III and II+III were lower than the activity of Complex III alone.
This may reflect the fact that Complexes I and II are present at lower concentrations than Complex III in the mitochondrial membrane [22], [23], and coupling Complex III to other enzymes may blunt the “excess” capacity of this enzyme.
结果:
为了研究一个包含辅酶Q的系统，我们还测量了配合物I+III和配合物II+III的活性。
与对照组小鼠相比，fat-1小鼠复合物I的活性降低了19% (p<0.05)。
相比之下，Complex III和Complex IV在fat-1小鼠肝脏线粒体中的活性分别提高了58% (p<0.01)和27% (p<0.05)。
复合物I活性的降低并不足以导致复合物I+III活性的整体下降，事实上，在脂肪-1动物中复合物I+III活性增加了19% (p<0.05)。
Complex II和Complex +III活性在对照组和fat-1小鼠之间无显著差异。
复合物I+III和II+III的活性低于复合物III单独的活性。
这可能反映了复合物I和II在线粒体膜[22]，[23]中比复合物III的浓度低，复合物III与其他酶偶联可能会钝化该酶的“过剩”能力。
We see the same shift as in the previous experiment. Note that this was under conditions with not much added stress (unlike the previous experiment which added Ca2+ and ROS stress).
我们看到了与之前实验相同的变化。需要注意的是，这是在没有增加太多应激的条件下进行的(不像之前的实验增加了Ca2+和ROS应激)。
They then measured H2O2 production as a marker for ROS generation potential:
Under substrate-only conditions, a significant decrease was observed in fat-1 H2O2 production in mitochondria respiring on succinate (p<0.05) and succinate/glutamate/malate (p<0.05).
After addition of rotenone, fat-1 mitochondria respiring on succinate/glutamate/malate, glutamate/malate or pyruvate/malate produced significantly less H2O2 when compared to controls (p<0.01).
After addition of antimycin a, fat-1 H2O2 production was significantly decreased when succinate was the substrate (p<0.001). However, with all other substrates, no significant differences in H2O2 production.
The results indicate that H2O2 production was greatly decreased in fat-1 liver mitochondria under conditions of maximum ROS production from complex I by forward (rotenone with complex I linked substrates) or reverse (succinate or succinate with antimycin A) electron flow.
然后，他们测量了H2O2的产生，作为活性氧产生潜力的标记:
在只添加底物的条件下，琥珀酸(p<0.05)和琥珀酸/谷氨酸/苹果酸(p<0.05)对线粒体呼吸产生的脂肪-1 H2O2显著降低(p<0.05)。
添加鱼藤酮后，琥珀酸/谷氨酸/苹果酸、谷氨酸/苹果酸或丙酮酸/苹果酸对脂肪-1线粒体呼吸产生的H2O2显著低于对照组(p<0.01)。
添加抗霉素a后，以琥珀酸为底物时，脂肪-1 H2O2产量显著降低(p<0.001)。然而，与其他基质相比，H2O2的产生没有显著差异。
结果表明，在复合物I通过正向(鱼藤酮与复合物I连接的底物)或反向(琥珀酸或琥珀酸与抗霉素A)电子流产生最大ROS的条件下，脂肪-1肝脏线粒体的H2O2产量大大降低。
Again, we see the same sorts of findings. Reduced ROS production along with reduced Complex 1 activity.
There was no difference in proton leak (and thus ATP generation potential):
There were no differences in maximal leak-dependent respiration and membrane potential (points farthest to the right in the graph) between the two groups of mice.
我们再次看到了相同的发现。活性氧生成减少，复合物1活性降低。
质子泄漏没有差异(因此ATP产生电位也没有差异):
两组小鼠的最大泄漏依赖呼吸和膜电位(图中最右边的点)没有差异。
The high DHA mitochondria are more prone to oxidative damage under “stressed” conditions, but not under regular basal metabolic conditions:
A significant increase (P<0.05) in mitochondrial membrane lipid peroxidation was observed in the fat-1 mice following stimulation of peroxidation with 2,2′-azobis(2-amidinopropane) (AAPH). This result indicates that the increase in membrane n-3 fatty acids in the fat-1 mice is associated with an increase in susceptibility to peroxidation when faced with an oxidative insult
It was necessary next to determine if alterations in mitochondrial lipid peroxidation occurred in the fat-1 animals under basal conditions.
Two methods, malondialdehyde (MDA) and 4-hydroxynonenal (HNE), were also used to provide an indication of basal levels of lipid peroxidation in mitochondria from the fat-1 mice (Figure 5A and 5B). In contrast to the AAPH results, no differences (P>0.05) in MDA or HNE levels were observed in mitochondria from the two groups of mice. These results indicate that despite elevated n-3 levels, basal lipid peroxidation is not increased in mitochondria from 1 year old fat-1 mice.
高DHA线粒体在“压力”条件下更容易发生氧化损伤，但在常规的基础代谢条件下则不会:
2,2′-偶氮(2-脒基丙烷)(AAPH)刺激fat-1小鼠线粒体膜脂过氧化显著增加(P<0.05)。这一结果表明，脂肪-1小鼠中膜n-3脂肪酸的增加与氧化损伤时过氧化敏感性的增加有关。
接下来有必要确定在基础条件下，脂肪-1动物线粒体脂质过氧化是否发生了改变。
两种方法，丙二醛(MDA)和4-羟基壬烯醛(HNE)，也被用来提供脂肪-1小鼠线粒体脂质过氧化基础水平的指示(图5A和5B)。
与AAPH结果相反，两组小鼠线粒体MDA和HNE水平无差异(P>0.05)。这些结果表明，尽管n-3水平升高，但1岁大的fat-1小鼠线粒体的基础脂质过氧化没有增加。
Apoptotic Regulation
凋亡调控
Mitochondria send the signals which determine their own and their host cells' survival. Any change to respiration mechanics will change the autophagic and apoptotic signals and signalling contexts.
线粒体发出的信号决定了它们自己和宿主细胞的生存。呼吸机制的任何改变都会改变自噬和凋亡信号和信号传递环境。
Since the sections above showed reductions in respiration capacity with DHA incorporation, I want to infer that DHA increases the signal threshold required for autophagy and apoptosis (making these actions less likely).
由于上面的章节显示了DHA加入后呼吸能力的降低，我想推断DHA增加了自噬和凋亡所需的信号阈值(使这些行为不太可能发生)。
Cardiac Cells
心肌细胞
Well, the context seems to depend on the cell tested. First, cardiac mitochondria, 'Improved Mitochondrial Function with Diet-Induced Increase in Either Docosahexaenoic Acid or Arachidonic Acid in Membrane Phospholipids' (Khairallah et. al., 2012) – http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034402#pone.0034402-Khairallah1
Don't be misled by the title; “improvements” is not the correct word to describe the changes observed (it requires context qualification to determine if the change is good or bad or inconsequential).
情况似乎取决于测试的细胞。首先，心脏线粒体，“通过饮食诱导膜磷脂中二十二碳六烯酸或花生四烯酸的增加，改善线粒体功能”(Khairallah等人，2012)——http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034402#pone.0034402-Khairallah1
不要被标题所误导;“改进”不是描述观察到的更改的正确词汇(它需要上下文限定来确定更改是好是坏还是无关紧要)。
Firstly, this study used quite a fair bit of DHA supplementation (2.5% of total energy intake) on rats to induce DHA incorporation into cardiac mitochondria. This is a stupidly high intake (7g of DHA if you consume 2500kcal a day). Whether or sane consumption of DHA can achieve the same degree of DHA incorporation into cardiac mitochondria of humans is not known. This alone makes the study somewhat un-useful.
首先，本研究对大鼠进行了相当多的DHA补充(总能量摄入的2.5%)，诱导DHA进入心肌线粒体。这是一个愚蠢的高摄入量(7克DHA，如果你每天摄入2500千卡)。DHA的合理消耗是否能达到同样程度的DHA融入人类心脏线粒体尚不清楚。仅这一点就使这项研究有些无用。
In any case, let's assume that this is possible, and DHA in cardiac mitochondrial membranes is doubled from 10% to 20% of total fatty acids like this study suggests.
The results were that:
Not much difference in State 3 and State 4 respiration; Substrate can still be used normally.
Sidenote: cardiac mitochondria seem to be a little special in this way – that they can use up any form of substrate supplied to them. As we saw in the sections above, this sort of behaviou is not typical.Mitochondrial MPTP apoptotic threshold increased
The authors clarify:
Mitochondria can depolarize and trigger cell death through the opening of the mitochondrial permeability transition pore (MPTP).
Results:
Mitochondria from rats supplemented with DHA or ARA alone had significantly enhanced Ca2+ retention capacity compared to CTRL animals, as reflected by significantly lower.
extramitochondrial [Ca2+] for a given cumulative Ca2+ load with all substrates except palmitoylcarnitine+malate.
a large increase in either DHA or ARA in mitochondrial membrane phospholipids is associated with a significant increase in the mitochondrial capacity for Ca2+ retention, an index of MPTP opening.
On the other hand, the extreme increase in the sum of ARA and DHA accompanied by depletion of linoleic acid that occurred with the DHA+ARA diet was associated with increased susceptibility to MPTP opening, and suggests that the combination of elevated DHA and ARA with low linoleic acid in membrane phospholipids is detrimental.
无论如何，让我们假设这是可能的，正如这项研究表明的那样，心脏线粒体膜中的DHA从总脂肪酸的10%翻倍到20%。
结果是:
状态3和状态4的呼吸差异不大;承印物仍可正常使用。
旁注:心脏线粒体似乎在这方面有一点特殊——它们可以消耗供给它们的任何形式的底物。正如我们在上面的章节中看到的，这种行为并不典型。
线粒体MPTP凋亡阈值升高
作者澄清:
线粒体可通过打开线粒体通透性过渡孔(MPTP)去极化并触发细胞死亡。
结果:
与对照组相比，单独添加DHA或ARA的大鼠的线粒体显著提高了Ca2+的保留能力，
表现为在给定的累积Ca2+负荷下，除棕榈肉碱+苹果酸外，所有底物的线粒体外[Ca2+]显著降低。
线粒体膜磷脂中DHA或ARA的大量增加与线粒体Ca2+保留能力的显著增加有关，这是MPTP开放的一个指标。
另一方面,极端ARA的总和和DHA伴随着损耗发生的亚油酸与DHA + ARA饮食与注射对MPTP药物增加有关,并表明,较低的高DHA和ARA亚油酸在膜磷脂是有害的。
All that is resonable, but even the authors admit that they assume a Ca2+ stressed state in this experiment, and state:
A second important limitation is that lack of measurement of the initial mitochondrial [Ca2+], as dietary supplementation with DHA or ARA could affect the residual Ca2+ in the mitochondrial matrix following isolation. Decreased initial matrix [Ca2+] could increase mitochondrial Ca2+ uptake capacity and give the impression of delayed PTP opening in response to successive Ca2+ additions.
Our main conclusion regarding mitochondrial Ca2+ retention is that dietary supplementation with docosahexaenoic acid or arachidonic acid are associated with a greater exogenous Ca2+ load required to induce MPTP opening.
We know of no rationale to suggest there would be differences in the initial [Ca2+] among treatment groups, nevertheless there may be differences that could affect the capacity for Ca2+ retention.
所有这些都是合理的，但即使是作者也承认，他们在这个实验中假设了一个Ca2+压力状态，并说:
第二个重要的限制是缺乏对初始线粒体[Ca2+]的测量，因为在膳食中补充DHA或ARA可能会影响分离后线粒体基质中残留的Ca2+。降低初始基质[Ca2+]可增加线粒体Ca2+摄取能力，并在连续Ca2+添加的反应中给人延迟PTP开放的印象。
我们关于线粒体Ca2+保留的主要结论是，膳食中添加二十二碳六烯酸或花生四烯酸与诱导MPTP开放所需的更大的外源Ca2+负荷相关。
我们知道没有理由表明在初始[Ca2+]治疗组之间存在差异，尽管如此，可能存在影响Ca2+保留能力的差异。
Regardless of what model of the cell membrane you use (though I much prefer Gilbert Ling's), Ca2+ is excluded by the membrane under normal conditions. The Ling model is appealing because it links ATP depletion directly to loss of membrane barrier function.
In the Ling model, not enough ATP implies that proteins cannot maintain their extended conformation to create large sheaths of polarised water / EZ water, which is what naturally excludes various solutes (see the experimental work of Gerald Pollack).
不管你使用什么模型的细胞膜(尽管我更喜欢Gilbert Ling的)，Ca2+在正常情况下被膜排除在外。Ling模型之所以吸引人，是因为它将ATP耗尽直接与膜屏障功能的丧失联系起来。
在Ling模型中，没有足够的ATP意味着蛋白质不能维持其延伸的构象来产生大的极化水/ EZ水鞘，这自然排除了各种溶质(见Gerald Pollack的实验工作)。
Some may not favour these models, but regardless of what model you use, the lost of solute homeostasis empirically comes down to the lack of the ability to maintain barrier function due to energetic loss. All models will agree that ATP is the currency for energy. Lack of ATP ⇒ uncontrolled calcium infux.
Let's ignore direct insults to cell membranes for now, which can occur from any number of mechanical forces – from being sliced by a blade, to getting bombarded by high powered EMF. The types of damage we are concerned with are usually chronic, and metabolic in nature.
有些人可能不喜欢这些模型，但不管你使用什么模型，从经验上讲，溶质稳态的丧失归结为由于能量损失而缺乏维持屏障功能的能力。所有的模型都同意ATP是能量的货币。缺乏ATP ⇒无控制的钙流入。
现在让我们先忽略对细胞膜的直接伤害，这可能来自任何数量的机械力——从被刀片划伤，到受到高能电磁场的轰击。我们所关心的损伤类型通常是慢性的，本质上是新陈代谢的。
In this regard, one can possibly come to the conclusion that there are multiple opposing forces at work here.
•(1) DHA can reduce Complex 1 activity and lead to lowered respiration and decreased ATP. This pre-disposes the cell to Ca2+ concentration dysregulation
•(2) DHA can increase the threshold for Ca2+ induced apoptosis
In cardiac cells, DHA doesn't affect (1) locally, so we have to look at non-local (wrt heart) means of Ca2+ influx excess. This is a very complex topic, with so many regulatory mechanisms which span all systems of the body – everything from direct dietary intake, to hypothalamic water regulation, to various excretion mechanics involving the liver and other oragns.
在这方面，人们可能会得出这样的结论:这里有多种相反的力量在起作用。
(1) DHA可降低Complex 1活性，导致呼吸降低，ATP减少。这使细胞易于Ca2+浓度失调
(2) DHA能提高Ca2+诱导的细胞凋亡阈值
在心脏细胞中，DHA不影响(1)局部，所以我们必须着眼于非局部(wrt心脏)Ca2+内流过量的方式。这是一个非常复杂的话题，有如此多的调节机制，跨越身体的所有系统——从直接饮食摄入，到下丘脑水的调节，到涉及肝脏和其他器官的各种排泄机制。
Trying to come to a conclusion that “DHA is good” based on such a study is not plausible.
For one, we need the assume that all cells control MPTP-to-apoptosis regulation the same way as there specific cardiac mitochondria. Given that substrate effects are different, how can we be confident that MPTP behaves the same universally?
How can we figure out what conditions induce Ca2+ damage? Is Ca2+ the most important signalling agent under those conditions? What about other “metabolic poisons” like Nitric Oxide which can lead to the same effects? Is apoptosis even a bad thing for the specific cell in question?
I don't know, and the likelihood of figuring such things out is basically close to 0%. Therefore, I will not use such information to make decisions about whether or not to consume more DHA (especially given the evidence against mitochondrial function).
试图根据这样的研究得出“DHA有益健康”的结论是不合理的。
首先，我们需要假设所有细胞控制mptp到凋亡的方式与特定的心肌线粒体相同。既然底物效应是不同的，我们怎么能确信MPTP的行为是普遍的呢?
我们怎么知道是什么条件导致Ca2+损伤?在这些条件下Ca2+是最重要的信号载体吗?那么其他的“代谢毒素”呢?比如一氧化氮，它也会导致同样的后果。细胞凋亡对特定的细胞来说是一件坏事吗?
我不知道，找出这些东西的可能性基本上接近于0%。因此，我不会使用这些信息来决定是否消耗更多的DHA(特别是考虑到线粒体功能的证据)。
Speculations and Practical Considerations
投机和实际考虑
We can speculate that having DHA incorporated into mitochondrial membranes signals a sort of “maintain the status quo” metabolism.
Which is to say:
•reduce metabolic capacity in general, especially through Complex 1
•prefer the use of fatty acids as a substrate for ATP generation
•reduce ROS generation and therefore the autophagic or apoptotic signal for existing mitochondria
我们可以推测，将DHA纳入线粒体膜是一种“维持现状”代谢的信号。
也就是说:
总体上降低代谢能力，特别是通过Complex 1
更喜欢使用脂肪酸作为生成ATP的底物
减少ROS的生成，从而抑制现有线粒体的自噬或凋亡信号。
Works great as a “hibernation strategy”, whereby external stressors and activity levels are probably low, while allowing the mitochondria to more readily feed off body fat stores. Probably not so good for a hard-charging athlete.
Note however that we have no way to measure “excess DHA”.
A person who has eaten a lot of DHA in the past may hold it in their adipose tissue, where it has no effect on said mitochondrial function, only to have them be liberated later on and become incorporated into mitochondrial membranes.
作为一种“冬眠策略”非常有效，外部压力源和活动水平可能很低，同时允许线粒体更容易消耗身体脂肪储备。对一个精力充沛的运动员来说可能不太好。
但是请注意，我们没有办法测量“多余的DHA”。
一个在过去吃了大量DHA的人可能会将其储存在脂肪组织中，而在脂肪组织中DHA对线粒体功能没有影响，只是在稍后它们被释放出来并并入线粒体膜。
Mitochondria also constantly get recycled, especially in tissues like the liver, so the state of membrane lipids is going to vary almost on a day to day basis (and definitely on a seasonal basis).
This is a system in constant flux, and trying to predict the state of mitochondrial function can't be measured in real time. We are left with using indirect measures of metabolism, and that is a whole different topic to discuss, and will not be discussed here.
As for DHA, too much dietary DHA is obviously still bad. The ideal case would be to limit it to the minimum required.
线粒体也在不断被循环利用，特别是在肝脏这样的组织中，所以膜脂的状态几乎每天都在变化(当然还有季节性的变化)。
这是一个不断变化的系统，试图预测线粒体功能的状态是无法实时测量的。我们剩下的是使用间接的代谢测量，这是一个完全不同的话题，我们不会在这里讨论。
至于DHA，饮食中摄入过多的DHA显然还是不好的。理想的情况是将其限制在所需的最低限度。
Low-Level DHA Mechanics
低级DHA力学
This section is speculatory. It attempts to incorporate physical properties of atoms together with the most plausible model of membrane mechanics (Gilbert Ling's) in an attempt to explain from a charge withdrawal / donation perspective, the physical mechanics of DHA.
这部分是推测性的。它试图将原子的物理性质与最合理的膜力学模型(Gilbert Ling的)结合在一起，试图从电荷提取/捐赠的角度来解释DHA的物理力学。
One thing that we do know is that DHA is probably not directly involved in any reaction (where charge transfer happens). It is so volatile to begin with, and if it were the site of energy transfer, so much of it would get degraded so quick that it's utility would be nil.
The most likely function of this compound, and why it has been preserved for biological use for so long, definitely has everything to do with it's 6 C=C bonds, and the ability for it to create a specific environment on cell membranes just by its mere presence.
While I say it is not a site of energy transfer, it can very well participate in attractive and repulsive behaviour with non-reactive compounds, which is obviously useful for biology to use as a “traffic director” for other molecules.
我们知道的一件事是DHA可能不直接参与任何反应(发生电荷转移)。它一开始就很不稳定，如果它是能量传递的场所，那么它的大部分会迅速降解，以至于它的效用将为零。
这种化合物最有可能的功能，以及为什么它能被保存这么长时间作为生物用途，肯定与它的6c =C键有关，以及它仅凭存在就能在细胞膜上创造特定环境的能力。
虽然我说它不是能量转移的场所，但它可以很好地参与非活性化合物的吸引和排斥行为，这显然是有用的，生物学上用作其他分子的“交通主管”。
